package com.example.ykbboom.universitytransportation.View;

import android.view.View;
import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.Paint.FontMetricsInt;
import android.graphics.Paint.Style;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import com.example.ykbboom.universitytransportation.POJO.Distance;
@SuppressLint({ "HandlerLeak", "ClickableViewAccessibility" })
public class PickerScrollView extends View {

        public static final String TAG = PickerScrollView.class.getSimpleName();
        /**
         * text之间间距和minTextSize之比
         */
        public static final float MARGIN_ALPHA = 2.8f;
        /**
         * 自动回滚到中间的速度
         */
        public static final float SPEED = 2;

        private List<Distance> mDataList;
        /**
         * 选中的位置，这个位置是mDataList的中心位置，一直不变
         */
        private int mCurrentSelected;
        private Paint mPaint;

        private float mMaxTextSize = 20;
        private float mMinTextSize = 10;

        private float mMaxTextAlpha = 255;
        private float mMinTextAlpha = 120;

        private int mColorText = 0x333333;

        private int mViewHeight;
        private int mViewWidth;

        private float mLastDownY;
        /**
         * 滑动的距离
         */
        private float mMoveLen = 0;
        private boolean isInit = false;
        private onSelectListener mSelectListener;
        private Timer timer;
        private MyTimerTask mTask;

        Handler updateHandler = new Handler() {

            @Override
            public void handleMessage(Message msg) {
                if (Math.abs(mMoveLen) < SPEED) {
                    mMoveLen = 0;
                    if (mTask != null) {
                        mTask.cancel();
                        mTask = null;
                        performSelect();
                    }
                } else
                    // 这里mMoveLen / Math.abs(mMoveLen)是为了保有mMoveLen的正负号，以实现上滚或下滚
                    mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;
                invalidate();
            }

        };

        public PickerScrollView(Context context) {
            super(context);
            init();
        }

        public PickerScrollView(Context context, AttributeSet attrs) {
            super(context, attrs);
            init();
        }

        public void setOnSelectListener(onSelectListener listener) {
            mSelectListener = listener;
        }

        private void performSelect() {
            if (mSelectListener != null)
                mSelectListener.onSelect(mDataList.get(mCurrentSelected));
        }

        public void setData(List<Distance> datas) {
            mDataList = datas;
            mCurrentSelected = datas.size() / 2;
            invalidate();
        }

        /**
         * 选择选中的item的index
         *
         * @param selected
         */
        public void setSelected(int selected) {
            mCurrentSelected = selected;
            int distance = mDataList.size() / 2 - mCurrentSelected;
            if (distance < 0)
                for (int i = 0; i < -distance; i++) {
                    moveHeadToTail();
                    mCurrentSelected--;
                }
            else if (distance > 0)
                for (int i = 0; i < distance; i++) {
                    moveTailToHead();
                    mCurrentSelected++;
                }
            invalidate();
        }

        /**
         * 选择选中的内容
         *
         * @param mSelectItem
         */
        public void setSelected(String mSelectItem) {
            for (int i = 0; i < mDataList.size(); i++)
                if (mDataList.get(i).equals(mSelectItem)) {
                    setSelected(i);
                    break;
                }
        }

        private void moveHeadToTail() {
            Distance head = mDataList.get(0);
            mDataList.remove(0);
            mDataList.add(head);
        }

        private void moveTailToHead() {
            Distance tail = mDataList.get(mDataList.size() - 1);
            mDataList.remove(mDataList.size() - 1);
            mDataList.add(0, tail);
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            mViewHeight = getMeasuredHeight();
            mViewWidth = getMeasuredWidth();
            // 按照View的高度计算字体大小
            mMaxTextSize = mViewHeight / 8.0f;
            mMinTextSize = mMaxTextSize / 2f;
            isInit = true;
            invalidate();
        }

        private void init() {
            timer = new Timer();
            mDataList = new ArrayList<Distance>();
            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mPaint.setStyle(Style.FILL);
            mPaint.setTextAlign(Align.CENTER);
            mPaint.setColor(mColorText);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            // 根据index绘制view
            if (isInit)
                drawData(canvas);
        }

        private void drawData(Canvas canvas) {
            // 先绘制选中的text再往上往下绘制其余的text
            float scale = parabola(mViewHeight / 4.0f, mMoveLen);
            float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
            mPaint.setTextSize(size);
            mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
            // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标
            float x = (float) (mViewWidth / 2.0);
            float y = (float) (mViewHeight / 2.0 + mMoveLen);
            FontMetricsInt fmi = mPaint.getFontMetricsInt();
            float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));

            int indexs = mCurrentSelected;
            String textData = mDataList.get(indexs).getDistance();
            canvas.drawText(textData, x, baseline, mPaint);

            // 绘制上方data
            for (int i = 1; (mCurrentSelected - i) >= 0; i++) {
                drawOtherText(canvas, i, -1);
            }
            // 绘制下方data
            for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {
                drawOtherText(canvas, i, 1);
            }
        }

        /**
         * @param canvas
         * @param position
         *            距离mCurrentSelected的差值
         * @param type
         *            1表示向下绘制，-1表示向上绘制
         */
        private void drawOtherText(Canvas canvas, int position, int type) {
            float d = (float) (MARGIN_ALPHA * mMinTextSize * position + type
                    * mMoveLen);
            float scale = parabola(mViewHeight / 4.0f, d);
            float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
            mPaint.setTextSize(size);
            mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
            float y = (float) (mViewHeight / 2.0 + type * d);
            FontMetricsInt fmi = mPaint.getFontMetricsInt();
            float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));

            int indexs = mCurrentSelected + type * position;
            String textData = mDataList.get(indexs).getDistance();
            canvas.drawText(textData, (float) (mViewWidth / 2.0), baseline, mPaint);
        }

        /**
         * 抛物线
         *
         * @param zero
         *            零点坐标
         * @param x
         *            偏移量
         * @return scale
         */
        private float parabola(float zero, float x) {
            float f = (float) (1 - Math.pow(x / zero, 2));
            return f < 0 ? 0 : f;
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            switch (event.getActionMasked()) {
                case MotionEvent.ACTION_DOWN:
                    doDown(event);
                    break;
                case MotionEvent.ACTION_MOVE:
                    doMove(event);
                    break;
                case MotionEvent.ACTION_UP:
                    doUp(event);
                    break;
            }
            return true;
        }

        private void doDown(MotionEvent event) {
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
            mLastDownY = event.getY();
        }

        private void doMove(MotionEvent event) {

            mMoveLen += (event.getY() - mLastDownY);

            if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2) {
                // 往下滑超过离开距离
                moveTailToHead();
                mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;
            } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {
                // 往上滑超过离开距离
                moveHeadToTail();
                mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;
            }

            mLastDownY = event.getY();
            invalidate();
        }

        private void doUp(MotionEvent event) {
            // 抬起手后mCurrentSelected的位置由当前位置move到中间选中位置
            if (Math.abs(mMoveLen) < 0.0001) {
                mMoveLen = 0;
                return;
            }
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
            mTask = new MyTimerTask(updateHandler);
            timer.schedule(mTask, 0, 10);
        }

        class MyTimerTask extends TimerTask {
            Handler handler;

            public MyTimerTask(Handler handler) {
                this.handler = handler;
            }

            @Override
            public void run() {
                handler.sendMessage(handler.obtainMessage());
            }

        }

        public interface onSelectListener {
            void onSelect(Distance distance);
        }
    }

